But the panel voted 21-5 that the contraceptives’ labels don’t adequately reflect that risk/benefit profile.

The newer oral contraceptives, which contain the man-made hormone drospirenone, include Bayer Healthcare Pharmaceutical's Beyaz, Safyral, Yasmin, and Yaz brands, as well as several other brands (Gianvi, Loryna, Ocella, Syeda, and Zarah).

They’ve been marketed as having extra benefits such as treating acne and severe premenstrual symptoms.

All oral contraceptives carry a potential risk of blood clots, but publicly funded studies, including one of 800,000 women by the FDA, have linked the drospirenone-containing oral contraceptives to a higher risk of clots compared to the older contraceptives, which contain the hormone levonorgestrel.

The research shows that about 10 in 10,000 women taking the newer pills would get a blood clot per year, compared to 6 in 10,000 women taking the older pills.

However, research funded by Bayer has not shown an increased risk of clots in women who took Yasmin, an earlier version of Yaz.

Almost all of the studies have focused on Yasmin, which in 2001 was the first pill containing drospirenone to earn FDA approval.

No More Effective

There is no research to suggest that pills containing drospirenone are more effective at preventing pregnancy than other birth control pills. And most of the older oral contraceptives treat acne just as well, Adriane Fugh-Berman, MD, an associate professor in family medicine at Georgetown University, told the advisory panel.

But, Fugh-Berman said, makers of the older pills, many of which are generic, haven’t thought it a worthwhile investment to seek FDA approval to market their drugs for that purpose.

Much of the discussion at the day-long advisory committee meeting focused on whether Yasmin might have a higher or lower risk of blood clots compared to the older birth control pills.

Drospirenone seems to block androgens, often called “male hormones,” although women have small amounts of them. Because of this, FDA scientist Rita Ouellet-Hellstrom, PhD, MPH, said doctors have tended to prescribe oral contraceptives containing drospirenone to women with polycystic ovary syndrome, or PCOS, a condition in which there is an imbalance of female sex hormones.

In the FDA study, women on Yasmin were twice as likely to have acne, which can be a characteristic of PCOS, than those on older birth control pills, Ouellett-Hellstrom said. PCOS alone puts women at a higher risk of blood clots.

Obesity can also raise women’s risk of blood clots. David Grimes, MD, said obese women are 60% to 80% more likely to be prescribed an oral contraceptive containing drospirenone than non-obese women. Grimes, a clinical professor of obstetrics and gynecology at the University of North Carolina at Chapel Hill, was paid by Bayer to speak on behalf of its contraceptives at the advisory committee meeting.

Labeling Changes May Be Needed

Although the panel voted to keep the newer pills on the market, there was a strong divide among the experts.

Panelist Almut Winterstein, PhD, associate professor at the University of Florida College of Pharmacy, said the data also suggest Yasmin users are younger and healthier, so the increased risk of blood clots might actually be higher than the research has found. All birth control pills that contain estrogen and a progestin, including drospirenone, have a boxed warning on their labels about the risk of serious heart and blood-vessel problems such as blood clots in smokers over age 35.

The panel was nearly unanimous in saying the label on drospirenone contraceptives should explain even more clearly that some studies suggest they increase the risk of blood clots. But panelists questioned how to make that information comprehensible to doctors, let alone patients.

The FDA has not set a date to discuss the wording of the new labels.

SOURCES:Rita Ouellet-Hellstrom, PhD, MPH, FDA scientist.David Grimes MD, clinical professor of obstetrics and gynecology, University of North Carolina, Chapel Hill.Almut Winterstein, PhD, associate professor, University of Florida College of Pharmacy, Gainesville.Adriane Fugh-Berman, MD, associate professor of family medicine, Georgetown University School of Medicine, Washington, D.C.